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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef GCHashTable_h
#define GCHashTable_h
#include "mozilla/Maybe.h"
#include "js/GCPolicyAPI.h"
#include "js/HashTable.h"
#include "js/RootingAPI.h"
#include "js/TypeDecls.h"
class JSTracer;
namespace JS {
// Define a reasonable default GC policy for GC-aware Maps.
template <typename Key, typename Value>
struct DefaultMapEntryGCPolicy {
static bool traceWeak(JSTracer* trc, Key* key, Value* value) {
return GCPolicy<Key>::traceWeak(trc, key) &&
GCPolicy<Value>::traceWeak(trc, value);
}
};
// A GCHashMap is a GC-aware HashMap, meaning that it has additional trace
// methods that know how to visit all keys and values in the table. HashMaps
// that contain GC pointers will generally want to use this GCHashMap
// specialization instead of HashMap, because this conveniently supports tracing
// keys and values, and cleaning up weak entries.
//
// GCHashMap::trace applies GCPolicy<T>::trace to each entry's key and value.
// Most types of GC pointers already have appropriate specializations of
// GCPolicy, so they should just work as keys and values. Any struct type with a
// default constructor and trace function should work as well. If you need to
// define your own GCPolicy specialization, generic helpers can be found in
// js/public/TracingAPI.h.
//
// The MapEntryGCPolicy template parameter controls how the table drops entries
// when edges are weakly held. GCHashMap::traceWeak applies the
// MapEntryGCPolicy's traceWeak method to each table entry; if it returns true,
// the entry is dropped. The default MapEntryGCPolicy drops the entry if either
// the key or value is about to be finalized, according to its
// GCPolicy<T>::traceWeak method. (This default is almost always fine: it's hard
// to imagine keeping such an entry around anyway.)
//
// Note that this HashMap only knows *how* to trace, but it does not itself
// cause tracing to be invoked. For tracing, it must be used as
// Rooted<GCHashMap> or PersistentRooted<GCHashMap>, or barriered and traced
// manually.
template <typename Key, typename Value,
typename HashPolicy = js::DefaultHasher<Key>,
typename AllocPolicy = js::TempAllocPolicy,
typename MapEntryGCPolicy = DefaultMapEntryGCPolicy<Key, Value>>
class GCHashMap : public js::HashMap<Key, Value, HashPolicy, AllocPolicy> {
using Base = js::HashMap<Key, Value, HashPolicy, AllocPolicy>;
public:
using EntryGCPolicy = MapEntryGCPolicy;
explicit GCHashMap() : Base(AllocPolicy()) {}
explicit GCHashMap(AllocPolicy a) : Base(std::move(a)) {}
explicit GCHashMap(size_t length) : Base(length) {}
GCHashMap(AllocPolicy a, size_t length) : Base(std::move(a), length) {}
void trace(JSTracer* trc) {
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
GCPolicy<Value>::trace(trc, &e.front().value(), "hashmap value");
GCPolicy<Key>::trace(trc, &e.front().mutableKey(), "hashmap key");
}
}
bool traceWeak(JSTracer* trc) {
typename Base::Enum e(*this);
traceWeakEntries(trc, e);
return !this->empty();
}
void traceWeakEntries(JSTracer* trc, typename Base::Enum& e) {
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
if (!MapEntryGCPolicy::traceWeak(trc, &e.front().mutableKey(),
&e.front().value())) {
e.removeFront();
}
}
}
// GCHashMap is movable
GCHashMap(GCHashMap&& rhs) : Base(std::move(rhs)) {}
void operator=(GCHashMap&& rhs) {
MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
Base::operator=(std::move(rhs));
}
private:
// GCHashMap is not copyable or assignable
GCHashMap(const GCHashMap& hm) = delete;
GCHashMap& operator=(const GCHashMap& hm) = delete;
} MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS;
} // namespace JS
namespace js {
// HashMap that supports rekeying.
//
// If your keys are pointers to something like JSObject that can be tenured or
// compacted, prefer to use GCHashMap with StableCellHasher, which takes
// advantage of the Zone's stable id table to make rekeying unnecessary.
template <typename Key, typename Value,
typename HashPolicy = DefaultHasher<Key>,
typename AllocPolicy = TempAllocPolicy,
typename MapEntryGCPolicy = JS::DefaultMapEntryGCPolicy<Key, Value>>
class GCRekeyableHashMap : public JS::GCHashMap<Key, Value, HashPolicy,
AllocPolicy, MapEntryGCPolicy> {
using Base = JS::GCHashMap<Key, Value, HashPolicy, AllocPolicy>;
public:
explicit GCRekeyableHashMap(AllocPolicy a = AllocPolicy())
: Base(std::move(a)) {}
explicit GCRekeyableHashMap(size_t length) : Base(length) {}
GCRekeyableHashMap(AllocPolicy a, size_t length)
: Base(std::move(a), length) {}
bool traceWeak(JSTracer* trc) {
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
Key key(e.front().key());
if (!MapEntryGCPolicy::traceWeak(trc, &key, &e.front().value())) {
e.removeFront();
} else if (!HashPolicy::match(key, e.front().key())) {
e.rekeyFront(key);
}
}
return !this->empty();
}
// GCRekeyableHashMap is movable
GCRekeyableHashMap(GCRekeyableHashMap&& rhs) : Base(std::move(rhs)) {}
void operator=(GCRekeyableHashMap&& rhs) {
MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
Base::operator=(std::move(rhs));
}
} MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS;
template <typename Wrapper, typename... Args>
class WrappedPtrOperations<JS::GCHashMap<Args...>, Wrapper> {
using Map = JS::GCHashMap<Args...>;
using Lookup = typename Map::Lookup;
const Map& map() const { return static_cast<const Wrapper*>(this)->get(); }
public:
using AddPtr = typename Map::AddPtr;
using Ptr = typename Map::Ptr;
using Range = typename Map::Range;
Ptr lookup(const Lookup& l) const { return map().lookup(l); }
Range all() const { return map().all(); }
bool empty() const { return map().empty(); }
uint32_t count() const { return map().count(); }
size_t capacity() const { return map().capacity(); }
bool has(const Lookup& l) const { return map().lookup(l).found(); }
size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return map().sizeOfExcludingThis(mallocSizeOf);
}
size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return mallocSizeOf(this) + map().sizeOfExcludingThis(mallocSizeOf);
}
};
template <typename Wrapper, typename... Args>
class MutableWrappedPtrOperations<JS::GCHashMap<Args...>, Wrapper>
: public WrappedPtrOperations<JS::GCHashMap<Args...>, Wrapper> {
using Map = JS::GCHashMap<Args...>;
using Lookup = typename Map::Lookup;
Map& map() { return static_cast<Wrapper*>(this)->get(); }
public:
using AddPtr = typename Map::AddPtr;
struct Enum : public Map::Enum {
explicit Enum(Wrapper& o) : Map::Enum(o.map()) {}
};
using Ptr = typename Map::Ptr;
using Range = typename Map::Range;
void clear() { map().clear(); }
void clearAndCompact() { map().clearAndCompact(); }
void remove(Ptr p) { map().remove(p); }
AddPtr lookupForAdd(const Lookup& l) { return map().lookupForAdd(l); }
template <typename KeyInput, typename ValueInput>
bool add(AddPtr& p, KeyInput&& k, ValueInput&& v) {
return map().add(p, std::forward<KeyInput>(k), std::forward<ValueInput>(v));
}
template <typename KeyInput>
bool add(AddPtr& p, KeyInput&& k) {
return map().add(p, std::forward<KeyInput>(k), Map::Value());
}
template <typename KeyInput, typename ValueInput>
bool relookupOrAdd(AddPtr& p, KeyInput&& k, ValueInput&& v) {
return map().relookupOrAdd(p, k, std::forward<KeyInput>(k),
std::forward<ValueInput>(v));
}
template <typename KeyInput, typename ValueInput>
bool put(KeyInput&& k, ValueInput&& v) {
return map().put(std::forward<KeyInput>(k), std::forward<ValueInput>(v));
}
template <typename KeyInput, typename ValueInput>
bool putNew(KeyInput&& k, ValueInput&& v) {
return map().putNew(std::forward<KeyInput>(k), std::forward<ValueInput>(v));
}
};
} // namespace js
namespace JS {
// A GCHashSet is a HashSet with an additional trace method that knows
// be traced to be kept alive will generally want to use this GCHashSet
// specialization in lieu of HashSet.
//
// Most types of GC pointers can be traced with no extra infrastructure. For
// structs and non-gc-pointer members, ensure that there is a specialization of
// GCPolicy<T> with an appropriate trace method available to handle the custom
// type. Generic helpers can be found in js/public/TracingAPI.h.
//
// Note that although this HashSet's trace will deal correctly with moved
// elements, it does not itself know when to barrier or trace elements. To
// function properly it must either be used with Rooted or barriered and traced
// manually.
template <typename T, typename HashPolicy = js::DefaultHasher<T>,
typename AllocPolicy = js::TempAllocPolicy>
class GCHashSet : public js::HashSet<T, HashPolicy, AllocPolicy> {
using Base = js::HashSet<T, HashPolicy, AllocPolicy>;
public:
explicit GCHashSet(AllocPolicy a = AllocPolicy()) : Base(std::move(a)) {}
explicit GCHashSet(size_t length) : Base(length) {}
GCHashSet(AllocPolicy a, size_t length) : Base(std::move(a), length) {}
void trace(JSTracer* trc) {
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
GCPolicy<T>::trace(trc, &e.mutableFront(), "hashset element");
}
}
bool traceWeak(JSTracer* trc) {
typename Base::Enum e(*this);
traceWeakEntries(trc, e);
return !this->empty();
}
void traceWeakEntries(JSTracer* trc, typename Base::Enum& e) {
for (; !e.empty(); e.popFront()) {
if (!GCPolicy<T>::traceWeak(trc, &e.mutableFront())) {
e.removeFront();
}
}
}
// GCHashSet is movable
GCHashSet(GCHashSet&& rhs) : Base(std::move(rhs)) {}
void operator=(GCHashSet&& rhs) {
MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
Base::operator=(std::move(rhs));
}
private:
// GCHashSet is not copyable or assignable
GCHashSet(const GCHashSet& hs) = delete;
GCHashSet& operator=(const GCHashSet& hs) = delete;
} MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS;
} // namespace JS
namespace js {
template <typename Wrapper, typename... Args>
class WrappedPtrOperations<JS::GCHashSet<Args...>, Wrapper> {
using Set = JS::GCHashSet<Args...>;
const Set& set() const { return static_cast<const Wrapper*>(this)->get(); }
public:
using Lookup = typename Set::Lookup;
using AddPtr = typename Set::AddPtr;
using Entry = typename Set::Entry;
using Ptr = typename Set::Ptr;
using Range = typename Set::Range;
Ptr lookup(const Lookup& l) const { return set().lookup(l); }
Range all() const { return set().all(); }
bool empty() const { return set().empty(); }
uint32_t count() const { return set().count(); }
size_t capacity() const { return set().capacity(); }
bool has(const Lookup& l) const { return set().lookup(l).found(); }
size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return set().sizeOfExcludingThis(mallocSizeOf);
}
size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return mallocSizeOf(this) + set().sizeOfExcludingThis(mallocSizeOf);
}
};
template <typename Wrapper, typename... Args>
class MutableWrappedPtrOperations<JS::GCHashSet<Args...>, Wrapper>
: public WrappedPtrOperations<JS::GCHashSet<Args...>, Wrapper> {
using Set = JS::GCHashSet<Args...>;
using Lookup = typename Set::Lookup;
Set& set() { return static_cast<Wrapper*>(this)->get(); }
public:
using AddPtr = typename Set::AddPtr;
using Entry = typename Set::Entry;
struct Enum : public Set::Enum {
explicit Enum(Wrapper& o) : Set::Enum(o.set()) {}
};
using Ptr = typename Set::Ptr;
using Range = typename Set::Range;
void clear() { set().clear(); }
void clearAndCompact() { set().clearAndCompact(); }
[[nodiscard]] bool reserve(uint32_t len) { return set().reserve(len); }
void remove(Ptr p) { set().remove(p); }
void remove(const Lookup& l) { set().remove(l); }
AddPtr lookupForAdd(const Lookup& l) { return set().lookupForAdd(l); }
template <typename TInput>
void replaceKey(Ptr p, const Lookup& l, TInput&& newValue) {
set().replaceKey(p, l, std::forward<TInput>(newValue));
}
template <typename TInput>
bool add(AddPtr& p, TInput&& t) {
return set().add(p, std::forward<TInput>(t));
}
template <typename TInput>
bool relookupOrAdd(AddPtr& p, const Lookup& l, TInput&& t) {
return set().relookupOrAdd(p, l, std::forward<TInput>(t));
}
template <typename TInput>
bool put(TInput&& t) {
return set().put(std::forward<TInput>(t));
}
template <typename TInput>
bool putNew(TInput&& t) {
return set().putNew(std::forward<TInput>(t));
}
template <typename TInput>
bool putNew(const Lookup& l, TInput&& t) {
return set().putNew(l, std::forward<TInput>(t));
}
};
} /* namespace js */
#endif /* GCHashTable_h */